Here we report the results of excavation and interdisciplinary study of the largest child and camelid sacrifice known from the New World. Stratigraphy, associated artifacts, and radiocarbon dating indicate that it was a single mass killing of more than 140 children and over 200 camelids directed by the Chimú state, c. AD 1450. Preliminary DNA analysis indicates that both boys and girls were chosen for sacrifice. Variability in forms of cranial modification (head shaping) and stable isotope analysis of carbon and nitrogen suggest that the children were a heterogeneous sample drawn from multiple regions and ethnic groups throughout the Chimú state. The Huanchaquito-Las Llamas mass sacrifice opens a new window on a previously unknown sacrificial ritual from fifteenth century northern coastal Peru. While the motivation for such a massive sacrifice is a subject for further research, there is archaeological evidence that it was associated with a climatic event (heavy rainfall and flooding) that could have impacted the economic, political and ideological stability of one of the most powerful states in the New World during the fifteenth century A.D.

Machu Picchu originally functioned as a palace within the estate of the Inca emperor Pachacuti between ~1420 and 1532 CE. Before this study, little was known about the people who lived and died there, where they came from or how they were related to the inhabitants of the Inca capital of Cusco. We generated genome-wide data for 34 individuals buried at Machu Picchu who are believed to have been retainers or attendants assigned to serve the Inca royal family, as well as 34 individuals from Cusco for comparative purposes. When the ancient DNA results are contextualized using historical and archaeological data, we conclude that the retainer population at Machu Picchu was highly heterogeneous with individuals exhibiting genetic ancestries associated with groups from throughout the Inca Empire and Amazonia. The results suggest a diverse retainer community at Machu Picchu in which people of different genetic backgrounds lived, reproduced, and were interred together.